The Journal of comparative neurology
-
The nucleus reuniens (RE) is part of the midline thalamus and one of the major sources of thalamic inputs to the hippocampal formation and the medial prefrontal cortex. However, it not only sends strong efferents to these areas but is also heavily innervated by both brain regions. Based on its connectivity and supported by functional studies the RE has been suggested to represent a major hub in reciprocal hippocampal-prefrontal communication. ⋯ Because of the unique role of the mouse as a genetically accessible model system for mammalian brain circuit analysis we have mapped the afferent connectivity of the mouse RE using retrograde Fluoro-Gold tracing. Comparison with similar data from rats indicated a very high level of similarity in prefrontal and hippocampal afferents but some differences in afferent connectivity with other brain regions. In particular, our results suggest interspecies differences regarding the integration of the RE in circuits of fear, aversion, and defense.